It is time for a new era in Arabic Type Design. An era in which the script is the source of typographic information. What we ask for may sound obvious and it is. Understanding the script then moving to type is nowhere near innovative. In Arabic however - contrary to popular belief - this bridge has not yet been made.
The x-height refers to the distance between the baseline and the top of the lower case line in a typeface. Typically, this is the height of the letter x in the font (the source of the term).